Method of improving power control in a mobile radiocommunication system

ABSTRACT

A method of improving the performance of a mobile radiocommunication system. According to the invention, a network element, known as the first element of the network transmitting to mobile terminals, receives at least one datum from at least one other network element, known as the second network element, said datum indicating the initial transmission power for transmission to a mobile terminal, in the case of radio link reconfiguration between the first network element and the mobile terminal, which can product a change n the transmission power for the radio link.

The present invention relates generally to mobile radiocommunicationsystems.

The present invention relates in particular to systems using the CDMA(Code Division Multiple Access) technique.

The CDMA technique is used in particular in so-called third-generationsystems, such as, in particular, the Universal Mobile TelecommunicationSystem (UMTS) system.

Generally, mobile radiocommunication systems are subject tostandardization, and for a full description of these systems referencecan be made to the appropriate standards, published by the appropriatestandardization organizations.

The general architecture of a mobile radiocommunication system such as,in particular, a UMTS type system, is reviewed in FIG. 1. The systemcomprises a mobile radiocommunication network communicating with mobileterminals or UE (User Equipment) and with external networks (notspecifically illustrated).

The mobile radiocommunication network comprises:

a radio access network, or UTRAN (UMTS Terrestrial Radio AccessNetwork),

a core network, or CN.

The third-generation systems, in particular of UMTS type, use a W-CDMA(Wideband—Code Division Multiple Access) type radio access technology.The UTRAN comprises base stations or “nodes B”, and base stationcontrollers or radio network controllers (RNC). The UTRAN is connectedon the one hand to the mobile terminals UE, via an interface known asthe “Uu” interface (or radio interface), and on the other hand to the CNvia an interface known as the “Iu” interface. Within the UTRAN, thenodes B communicate with the RNCs via an interface known as the “lub”interface, and an interface known as the “lur” interface can also beprovided between RNCs.

For a given node B, the RNC that controls it is also called CRNC(Controlling Radio Network Controller). The CRNC has a load monitoringrole and monitors and allocates radio resources for the nodes B that itcontrols.

Furthermore, systems such as UMTS use the macro-diversity modetransmission technique (or “soft-handover”) according to which a UE canbe connected simultaneously to a number of nodes B, that is, be servedsimultaneously by a number of serving cells (or active cells).

For a given call relating to a given UE, there is an RNC, called SRNC(Serving Radio Network Controller), having a control role for the callconcerned, including radio link set-up and release control functions,and for controlling parameters that can change during a call, such asbit rate, power, spreading factor, etc. The various nodes B to which aUE is connected may or may not be controlled by one and the same RNC. Ifthey are controlled by different RNCs, one of the RNCs has an SRNC role,and the nodes B connected to the UE and not controlled by the SRNCcommunicate with the SRNC via the RNCs that control them, also calleddrift RNCs, or DRNC, via the “lur” interface.

As a general rule, different data types can be transmitted in thesesystems: data corresponding to user or traffic data, and datacorresponding to control or signaling data essential to systemoperation. Different protocols have been defined for the datainterchanges between various elements of these systems, in particular:

the RANAP (Radio Access Network Application Part) protocol, as definedin the 3GPP specification TS 25.413, for signaling interchanges betweenCN and RNC,

the RNSAP (Radio Network Subsystem Application Part) protocol, asdefined in the 3GPP specification TS 25.423, for signaling interchangesbetween RNCs interlinked by an “lur” interface,

the NBAP (Node B Application Part) protocol, as defined in the 3GPPspecification TS 25.433, for signaling interchanges between RNC and nodeB,

the RRC (Radio Resource Control) protocol, as defined in the 3GPPspecification TS 25.331, for signaling interchanges between RNC and UE.

Different channel types have been defined for the data interchangesbetween UE and UTRAN, corresponding to different levels of thecommunication protocol between UE and UTRAN, that is, from the highestlevel to the lowest level: logical channels, transport channels andphysical channels. There are different types of logical channels, inparticular according to the type of data to be transmitted. The data tobe transmitted can furthermore have bit rates that differ according tothe services and that vary during one and the same call for one and thesame service, these various constraints being taken into account attransport channel and physical channel level, through a number ofparameters used to define these channels, such as, in particular, thetransmission time interval (TTI), the channel-coding type, the spreadingfactor, etc.

It will also be recalled that a characteristic of the third generationsystems such as, in particular, UMTS, is the facility to transport anumber of services on one and the same connection, or a number oftransport channels on one and the same physical channel. For example, ina system such as UMTS, such transport channels (TrCH) are handledseparately according to a channel-coding scheme, before beingmultiplexed to form a coded composite transport channel (CCTrCH) to betransmitted on one or more physical channels. There can also be a numberof CCTrCH for one and the same connection. It should also be rememberedthat the transmission power is the same for all the transport channelsmultiplexed on one and the same CCTrCH transmitted on one and the samephysical channel (or DPDCH, dedicated physical data channel). Moreinformation on these aspects of UMTS can be found in particular in the3GPP specification TS 25.212.

As a general rule, the third-generation systems, in particular of UMTStype, need to be able to support traffic categories with quality ofservice (QoS) requirements that can differ widely from one to the next.To guarantee the quality of service at different levels of such asystem, a QoS architecture has been defined, in which different bearerservices are distinguished (such as, in particular: radio access bearer(RAB) services between CN and UE, radio bearer (RB) services between RNCand UE, etc), and different QoS attributes (such as, in particular, thetraffic class, maximum bit rate, guaranteed bit rate, transfer delay,etc).

The RNC handles in particular radio resource management functions, inorder, in particular, to guarantee system performance, in terms ofcapacity and quality of service.

In CDMA systems, the capacity limitations on the radio interface arefundamentally different from those that apply in systems using othermultiple access techniques, such as, in particular, the TDMA (TimeDivision Multiple Access) technique. The TDMA technique is in particularused in the so-called second-generation systems such as GSM (GlobalSystem for Mobile communications). In CDMA systems, all the users sharethe same frequency resource at all times. The capacity of these systemsis therefore limited by the interference factors, these systems alsobeing called for this reason “soft limited systems”.

This is why, in CDMA systems, the radio resource management functionsinclude in particular algorithms such as so-called load controlalgorithms to prevent overloads, detect them and correct them, andso-called radio admission control algorithms, to decide whether thecapacity of a cell that is not being used at a given instant issufficient to accept a call (that is, to set up a new radio link or anadditional radio link) in this cell, according to various parameterssuch as the service required for this call, the required quality ofservice, etc.

A typical radio admission control algorithm is based on the transmissionpower of the node B in the downlink direction, and on the interferencelevel in the uplink direction. More specifically, in the downlinkdirection, the radio admission algorithm checks whether there issufficient node B transmission power remaining to accept a new radiolink or an additional radio link. For such an algorithm, a major problemis therefore how to estimate what transmission power is required in thedownlink direction for a new radio link or an additional radio link. Theperformance of this algorithm and therefore the performance of thesystem depend on the quality of this estimation.

Moreover, the UMTS standard is flexible regarding the location of theradio admission algorithm in the system. In particular, such analgorithm can be implemented in the node B or in the RNC, even partly inone and partly in the other. If the radio admission algorithm or a partthereof is implemented in the node B, or in any case where a knowledgeof the initial power is necessary at the node B itself, for example,even to use this power as initial transmission power for the powercontrol algorithm, in particular to improve the performance of thisalgorithm, specific problems arise. These specific problems are due tothe fact that the estimation of the initial power by the node B itselfis difficult, because the node B does not have all the knowledgerequired for this estimation.

In particular, the node B has no knowledge of certain information thatthe RNC knows from its control functions. For example, the RNC knows thequality of service required for the call, which is communicated to it bythe CN during call set-up, and which is needed for radio bearer (RB)set-up. According to another example, for the case of transmission inmacro-diversity mode, the RNC knows the transmission power required forother radio links for the same UE with other nodes B, because the RNCitself determines a so-called reference transmission power for thedifferent radio links for one and the same UE with different nodes B.

This is why, in the current state of the UMTS standard, provision ismade for the RNC to signal to the node B (via the NBAP protocol) theinitial transmission power required for the downlink direction. However,in the current state of the standard, this is provided only for the caseof a new radio link (or radio link set up following receipt by the nodeB of the “radio link set-up” message) or for the case of an additionalradio link (or radio link set up following receipt by the node B of the“radio link addition” message).

However, as the applicant has observed, there is another case where itwould be important for the node B to know the transmission powerrequired for a radio link. This case corresponds to the case where aradio link is reconfigured (for example, when the spreading factor, orany parameter used to define the transport or physical channels for thisradio link) is changed, etc. For example, an important radio linkreconfiguration case is the one that occurs at the start of a call. Inpractice, when a call is set up:

in a first step, when a first radio link is set up, the RNC configuresonly the control channels, or DCCH (Dedicated Control Channel), orlogical channels used at the start of a call to transport the signalingaccording to the RRC (Radio Resource Control) protocol between RNC andUE and NAS (Non-Access Stratum) protocol between CN and UE,

then, in a second step, once the CN has determined how the call must behandled, and transmitted to the RNC the radio access bearer set-uprequest or RAB (RAB Assignment Request) message with information on theservice required and the required quality of service, the RNC sends tothe node B a radio link reconfiguration message, in order, inparticular, to add traffic channels, or DTCH (Dedicated Traffic Channel)logical channels and to change the parameters of the physical channels.This second step normally requires a significant increase intransmission power (in practice, typically, the bit rate transported bythe DCCH channels is only between 3 and 4 kbit/s, whereas the bit ratetransported by the DTCH channels can be much higher).

In the current state of the standard, no provision is made for the RNCto signal to the node B the initial transmission power required for thedownlink direction, following a radio link reconfiguration. Morespecifically, in the current state of the standard, for the UMTS FDD(Frequency Division Duplex) mode, provision is made only for the RNC tosignal to the node B the initial transmission power required for thedownlink direction, in a “Radio Link Set-up” message (in the case ofcreation of a new radio link) or “Radio Link Addition” message (in thecase of creation of an additional radio link). For the UMTS TDD (TimeDivision Duplex) mode, provision is also made for the RNC to signal tothe node B the initial transmission power required for the downlinkdirection, in a “Radio Link Reconfiguration Prepare” message, but, asindicated in the 3GPP specification TS 25.433, the initial transmissionpower signaled in this way is to be applied by the node B when it beginsto transmit on a new CCTrCH channel. Thus, this latter case correspondsto the case of creation of a new CCTrCH channel, and not to the case ofreconfiguration of an already created CCTrCH channel.

As the applicant has observed, radio link reconfiguration case istherefore not currently handled optimally. In particular, the case ofradio link reconfiguration which can result in a change in thetransmission power for at least one transmission entity on the radiolink, for which a transmission power can be defined (such a transmissionentity possibly corresponding in particular to a DPDCH channel, or to aCCTrCH channel, or, more generally, to any channel type for which thesame type of problem arises) is not taken into account. The result isdegraded performance, in particular a performance degradation affectingthe radio admission control and power control algorithms, or, moregenerally, a system performance degradation, in particular in terms ofcapacity and quality of service.

The main object of the present invention is to avoid all or some ofthese drawbacks and, more generally, to improve the performance of thesesystems.

One subject of the present invention is a method of improving theperformance of a mobile radiocommunication system, in which method anetwork element, known as the first network element, transmitting tomobile terminals, receives at least one information element from atleast one other network element, known as the second network element,said information element indicating the initial transmission power fortransmission to a mobile terminal, in the case of radio linkreconfiguration between said first network element and said mobileterminal, which can produce a change in the transmission power for thisradio link.

According to another characteristic, said first network elementcorresponds to a base station, or node B in a UMTS type system.

According to another characteristic, said second network elementcorresponds to a base station controller, or radio network controller(RNC) in a UMTS type system.

According to another characteristic, said second network elementcorresponds to a network element having a function for controllingcommunication with said mobile terminal, including a radio linkreconfiguration control function, in particular, in a UMTS Type system,a radio network controller or RNC having an SRNC (Serving Radio NetworkController) role.

According to another characteristic, said second network elementcorresponds to a network element controlling said first network element,in particular, in a UMTS type system, a radio network controller or RNCcontrolling a node B or having a CRNC (Controlling Radio NetworkController) role for this node B.

According to another characteristic, in particular in a UMTS typesystem, said information element indicating initial transmission poweris transmitted from an RNC having an SRNC role and a CRNC role for anode B, to this node B, according to the NBAP (Node B Application Part)protocol.

According to another characteristic, said second network elementcorresponds to a network element not controlling said first networkelement, and said first network element receives said informationelement indicating the initial transmission power, from said secondnetwork element, via a third network element controlling said firstnetwork element, in particular, in a UMTS type system, via a radionetwork controller or RNC having a DRNC (Drift Radio Network Controller)role.

According to another characteristic, in particular in a UMTS typesystem, said information element indicating initial transmission poweris transmitted from an RNC having an SRNC role, to an RNC having a DRNCrole and a CRNC role for a node B, according to the RNSAP (Radio NetworkSubsystem Application Part) protocol, then retransmitted from thislatter RNC to the node B, according to the NBAP (Node B ApplicationPart) protocol.

According to another characteristic, said information element isreceived in a radio link reconfiguration command message.

According to another characteristic, said information element isreceived in a synchronized radio link reconfiguration command message.

According to another characteristic, said information element isreceived in an unsynchronized radio link reconfiguration commandmessage.

According to another characteristic, in a UMTS type system, said radiolink reconfiguration command message corresponds to a “radio linkreconfiguration prepare” message.

According to another characteristic, in a UMTS type system, said radiolink reconfiguration command message corresponds to a “radio linkreconfiguration request” message.

According to another characteristic, said initial transmission power isused by said first network element for a radio admission controlalgorithm.

According to another characteristic, said initial transmission power isused by said first network element for a power control algorithm.

Another subject of the present invention is a network element, includingmeans for implementing a method according to the invention.

Another subject of the present invention is a base station controller,or node B, including means for implementing a method according to theinvention. Another subject of the present invention is a base stationcontroller, or radio network controller or RNC, including means forimplementing a method according to the invention.

Another subject of the present invention is a mobile radiocommunicationsystem, including means for implementing a method according to theinvention.

Another subject of the present invention is a base station controllerincluding means for transmitting to a base station at least oneinformation element indicating the initial transmission power fortransmission to a mobile terminal, in the case of radio linkreconfiguration between said base station and said mobile terminal,which can produce a change in the transmission power for this radiolink.

Another subject of the present invention is a base station controller,including means for transmitting to a base station controller at leastone information element indicating the initial transmission power fortransmission to a mobile terminal, in the case of radio linkreconfiguration between a base station and said mobile terminal, whichcan produce a change in the transmission power for this radio link.

Another subject of the present invention is a base station controller,including means for receiving from a base station controller at leastone information element indicating the initial transmission power fortransmission to a mobile terminal, in the case of radio linkreconfiguration between a base station and said mobile terminal, whichcan produce a change in the transmission power for this radio link, andfor retransmitting said information element to said base station.

Another subject of the present invention is a base station includingmeans for receiving from a base station controller at least oneinformation element indicating the initial transmission power fortransmission to a mobile terminal, in the case of radio linkreconfiguration between said base station and said mobile terminal,which can produce a change in the transmission power for this radiolink.

According to another characteristic, said base station includes meansfor using said information element for a radio admission controlalgorithm.

According to another characteristic, said base station includes meansfor using said information element for a power control algorithm.

Other objects and characteristics of the present invention will becomeapparent from reading the description that follows of exemplaryembodiments, given in relation to the appended drawings in which:

FIG. 1, described previously, reviews the general architecture of amobile radiocommunication system, such as, in particular, the UMTSsystem,

FIGS. 2 and 3 are diagrams for respectively illustrating a first and asecond exemplary embodiment of a method according to the invention.

The present invention can also be explained as follows.

The present invention proposes, in particular, to provide an estimationof the transmission power required in the downlink direction, in theRNC, and signal the duly obtained value to the node B, such that thenode B can use it as the initial transmission power and can also use itfor radio admission control, if the latter is implemented in the node B.

The present invention proposes in particular that the RNC signal to thenode B the initial transmission power of a radio link, in the case wherethis radio link is reconfigured (that is, in any case of change for thisradio link, that can produce a change in the transmission power). Inparticular, this can occur if physical or transport channel parametersare modified for this radio link (for example, the spreading factor, thechannel coding, the transmission time interval (TTI), etc), if transportchannels are added or deleted, if the service or quality of servicechanges, etc. As explained previously, a particular important radio linkreconfiguration case is the one that occurs at the start of a call.

Advantageously, the initial power for the downlink direction (or“Initial DL Power”, where DL stand for “Downlink”) for the reconfiguredradio link can be signaled in the same messages as those used toreconfigure the radio link.

It will be noted that there are different ways of reconfiguring a radiolink:

synchronized radio link reconfiguration,

unsynchronized radio link reconfiguration.

In this context, synchronization refers to the reconfiguration of allthe radio links at the same moment for the different nodes B with whicha UE is connected (in the case where a UE is in “soft-handover” modewith different nodes B).

In the synchronized reconfiguration case, two reconfiguration commandmessages are sent by the RNC to the node B:

“Radio Link Reconfiguration Prepare”,

“Radio Link Reconfiguration Commit”.

According to a preferred example, the message used to signal the initialtransmission power of a radio link in the case of reconfiguration ofthis radio link is the first message (Radio Link ReconfigurationPrepare), the second message (Radio Link Reconfiguration Commit)normally giving only the instant at which reconfiguration takes place,all the reconfiguration information being given in the first message.

In the case of unsynchronized reconfiguration, just one message is sentby the RNC to the node B:

“Radio Link Reconfiguration Request”.

The invention proposes in particular to add an information element (IE)called “Initial DL Transmission Power” to one and/or the other of thetwo aforementioned messages, that is “Radio Link ReconfigurationPrepare” and “Radio Link Reconfiguration Request”.

Also, the normal way of defining a transmission power, as defined inparticular in the 3GPP specification TS 25.433 is reviewed below:

for the FDD (Frequency Duplex Division) mode: the power level relativeto the power of the primary CPICH channel (where CPICH stands for“Common Pilot CHannel”) and by referring to the DPDCH (DedicatedPhysical Data Channel) symbols transmitted,

for the TDD mode: the power level relative to the power of the primaryCPICH channel.

The present invention thus proposes in particular that a networkelement, known as the first network element, transmitting to mobileterminals, receives at least one information element from at least oneother network element, known as the second network element, indicatingthe initial transmission power for transmission to a mobile terminal, inthe case of radio link reconfiguration between said first networkelement and said mobile terminal, which can produce a change in thetransmission power for this radio link.

In particular, said change in the transmission power corresponds to achange in the transmission power for at least one transmission entity onthis radio link, for which a transmission power can be defined.

Said first network element corresponds in particular to a base station,or node B in a UMTS type system.

Said second network element corresponds in particular to a base stationcontroller, or radio network controller (RNC), in a UMTS type system.

Said second network element can in particular correspond to a networkelement having a function for controlling communication with said mobileterminal, including a radio link reconfiguration control function, inparticular, in a UMTS type system, a radio network controller or RNChaving an SRNC (Serving Radio Network Controller) role.

According to a first embodiment, said second network element can inparticular correspond to a network element controlling said firstnetwork element, in particular, in a UMTS type system, a radio networkcontroller or RNC controlling a node B or having a CRNC (ControllingRadio Network Controller) role for this node B.

According to this first embodiment, in a UMTS type system, saidinformation element indicating the initial transmission power can inparticular be transmitted from an RNC having an SRNC role and a CRNCrole for a node B, to this node B, according to the NBAP (Node BApplication Part) protocol.

According to a second embodiment, said second network element can inparticular correspond to a network element not controlling said firstnetwork element, and said first network element can receive saidinformation element indicating the initial transmission power, from saidsecond network element, via a third network element controlling saidfirst network element, in particular, in a UMTS type system, via a radionetwork controller or RNC having a DRNC (Drift Radio Network Controller)role.

According to this second embodiment, in a UMTS type system, saidinformation element indicating the initial transmission power can inparticular be transmitted, from an RNC having an SRNC role, to an RNChaving a DRNC role and a CRNC role for a node B, according to the RNSAP(Radio Network Subsystem Application Part) protocol, then retransmittedfrom the latter RNC to the node B, according to the NBAP (Node BApplication Part) protocol.

In particular, said information element indicating the initialtransmission power can be transmitted in a radio link reconfigurationcommand message, synchronized or unsynchronized, in particular, in aUMTS type system, one and/or the other of the following messages,provided according to the NBAP and RNSAP protocols:

“Radio Link Reconfiguration Prepare”,

“Radio Link Reconfiguration Request”.

FIG. 2 is a diagram for illustrating an example of means that can beprovided to implement a method according to the invention, by way ofexample in a UMTS type system, and in the first exemplary embodimentmentioned above.

In this first exemplary embodiment, said information element indicatingthe initial transmission power is transmitted from an RNC, designatedRNC₁, having an SRNC role and a CRNC role for a node B, to this node B,for example in a reconfiguration command message transmitted accordingto the NBAP protocol.

RNC₁ thus includes (in addition to other means that can be conventionalmeans):

means designated 1 for transmitting said information element to the nodeB, in an NBAP message, for example a reconfiguration command messagesuch as “Radio Link Reconfiguration Prepare” or “Radio LinkReconfiguration Request”.

The node B thus comprises (in addition to other means that can beconventional means):

means designated 2 for receiving said information element from RNC₁,

means designated 3 for using said information element, for example for aradio admission control algorithm and/or a power control algorithm, asindicated previously.

FIG. 3 is a diagram for illustrating an example of means that can beprovided to implement a method according to the invention, as an examplein a UMTS type system, and in the second exemplary embodiment mentionedabove.

In this second exemplary embodiment, said information element indicatingthe initial transmission power is transmitted from an RNC, designatedRNC₂, having an SRNC role, to an RNC designated RNC₃, having a DRNC roleand a CRNC role for a node B, for example in a reconfiguration commandmessage transmitted according to the RNSAP protocol, then retransmittedfrom RNC₃ to the node B, for example in a reconfiguration commandmessage transmitted according to the NBAP protocol.

RNC₂ thus includes (in addition to other means that can be conventionalmeans):

means designated 4 for transmitting said information element to RNC₃, inan RNSAP message, for example a reconfiguration command message, such as“Radio Link Reconfiguration Prepare” or “Radio Link ReconfigurationRequest”.

RNC₃ thus includes (in addition to other means that can be conventionalmeans):

means designated 5 for retransmitting said information element to thenode B, in an NBAP message, for example a reconfiguration commandmessage, such as “Radio Link Reconfiguration Prepare” or “Radio LinkReconfiguration Request”.

The node B thus includes (in addition to other means that can beconventional means):

means designated 6 for receiving said information element from the RNC₃,

means designated 7 for using said information element, for example for aradio admission control algorithm and/or a power control algorithm, asindicated previously.

These various means can function according to the methods describedpreviously; since their particular embodiment presents no particulardifficulties for those skilled in the art, such means do not need to bedescribed here in any more detail than by their function.

1. Method of improving the performance of a mobile radiocommunicationsystem, in which method a network element, known as the first networkelement, transmitting to mobile terminals, receives at least oneinformation element from at least one other network element, known asthe second network element, said information element indicating theinitial transmission power for transmission to a mobile terminal, in thecase of radio link reconfiguration between said first network elementand said mobile terminal, which can produce a change in the transmissionpower for this radio link.
 2. Method according to claim 1, in which saidfirst network element corresponds to a base station, or node B in a UMTStype system.
 3. Method according to claim 1, in which said secondnetwork element corresponds to a base station controller, or radionetwork controller (RNC) in a UMTS type system.
 4. Method according toclaim 1, in which said second network element corresponds to a networkelement having a function for controlling communication with said mobileterminal, including a radio link reconfiguration control function, inparticular, in a UMTS type system, a radio network controller or RNChaving an SRNC (Serving Radio Network Controller) role.
 5. Methodaccording to claim 1, in which said second network element correspondsto a network element controlling said first network element, inparticular, in a UMTS type system, a radio network controller or RNCcontrolling a node B or having a CRNC (Controlling Radio NetworkController) role for this node B.
 6. Method according to claim 4, inwhich said second network element corresponds to a network elementcontrolling said first network element, in particular, in a UMTS typesystem, a radio network controller or RNC controlling a node B or havinga CRNC (Controlling Radio Network Controller) role for this node B, andfurther in which, in particular in a UMTS type system, said informationelement indicating initial transmission power is transmitted from an RNChaving an SRNC role and a CRNC role for a node B, to this node B,according to the NBAP (Node B Application Part) protocol.
 7. Methodaccording to claim 1, in which said second network element correspondsto a network element not controlling said first network element, andsaid first network element receives said information element indicatinginitial transmission power, from said second network element, via athird network element controlling said first network element, inparticular, in a UMTS type system, via a radio network controller or RNChaving a DRNC (Drift Radio Network Controller) role.
 8. Method accordingto claim 4, in which said second network element corresponds to anetwork element not controlling said first network element, and saidfirst network element receives said information element indicatinginitial transmission power, from said second network element, via athird network element controlling said first network element, inparticular, in a UMTS type system, via a radio network controller or RNChaving a DRNC (Drift Radio Network Controller) role, and further inwhich, in particular in a UMTS type system, said information elementindicating initial transmission power is transmitted from an RNC havingan SRNC role, to an RNC having a DRNC role and a CRNC role for a node B,according to the RNSAP (Radio Network Subsystem Application Part)protocol, then retransmitted from this latter RNC to the node B,according to the NBAP (Node B Application Part) protocol.
 9. Methodaccording to claim 1, in which said information element is received in aradio link reconfiguration command message.
 10. Method according toclaim 1, in which said information element is received in a synchronizedradio link reconfiguration command message.
 11. Method according toclaim 1, in which said information element is received in anunsynchronized radio link reconfiguration command message.
 12. Methodaccording to claim 9, in which, in a UMTS type system, said radio linkreconfiguration command message corresponds to a “radio linkreconfiguration prepare” message.
 13. Method according to claim 9, inwhich, in a UMTS type system, said radio link reconfiguration commandmessage corresponds to a “radio link reconfiguration request” message.14. Method according to claim 1, in which said initial transmissionpower is used by said first network element for a radio admissioncontrol algorithm.
 15. Method according to claim 1, in which saidinitial transmission power is used by said first network element for apower control algorithm.
 16. Network element, including means forimplementing a method according to claim
 1. 17. Base station controller(RNC₁), including means (1) for transmitting to a base station (node B)at least one information element indicating the initial transmissionpower for transmission to a mobile terminal (UE), in the case of radiolink reconfiguration between said base station and said mobile terminal,which can produce a change in the transmission power for this radiolink.
 18. Base station controller (RNC₂), including means (4) fortransmitting to a base station controller (RNC₃) at least oneinformation element indicating the initial transmission power fortransmission to a mobile terminal (UE), in the case of radio linkreconfiguration between a base station and said mobile terminal, whichcan produce a change in the transmission power for this radio link. 19.Base station controller (RNC₃), including means (5) for receiving from abase station controller (RNC₂) at least one information elementindicating the initial transmission power for transmission to a mobileterminal, in the case of radio link reconfiguration between a basestation and said mobile terminal, which can produce a change in thetransmission power for this radio link, and for retransmitting saidinformation element to said base station.
 20. Base station (node B)including means (2, 6) for receiving from a base station controller(RNC₁, RNC₃) at least one information element indicating the initialtransmission power for transmission to a mobile terminal (UE), in thecase of radio link reconfiguration between said base station and saidmobile terminal, which can produce a change in the transmission powerfor this radio link.
 21. Base station according to claim 20, includingmeans (3, 7) for using said information element for a radio admissioncontrol algorithm.
 22. Base station according to claim 20, includingmeans (3, 7) for using said information element for a power controlalgorithm.
 23. Mobile radiocommunication system, including means forimplementing a method according to claim 1.